One or more embodiments relate to a semiconductor device, in particular to a trench semiconductor device, in one embodiment a power semiconductor device. One or more embodiments also relate to a method of manufacturing a semiconductor device, a trench semiconductor device, in one embodiment a power semiconductor device.
Semiconductor devices using trench technology are used in a plurality of industrial fields. In particular, power semiconductor devices are used, e.g., in motor drive circuits, appliance controls, robotics and lighting ballasts.
In general, semiconductor devices using trench technology offer a significantly increased channel width per unit area as compared to planar devices, thereby enabling a higher load current per unit area. Further, semiconductor devices with trench technology offer superior switching characteristics and are often used in applications which demand fast switching. For example, a power FET usually has a source region near a first surface of a semiconductor substrate and a drain region near a second surface of the semiconductor substrate, while the gate is located in a trench extending downward from the first surface. The gate is normally insulated from the semiconductor substrate by a thin gate oxide layer. As the capacitance of the capacitor, formed by gate and semiconductor substrate with the gate oxide layer as dielectric in-between, is small, only small gate currents for charging and discharging the capacitor are needed, which results in fast switching.
A thin gate oxide layer may increase the leakage currents from the gate to other parts of the semiconductor device. In particular, defects of the gate oxide layer can be a weak point of the semiconductor device reducing its reliability and increasing defect rates.